Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 140952

Area Forecast Discussion
National Weather Service Boise ID
252 AM MST Thu Dec 14 2017

.SHORT TERM...Today through Friday...The influence of the Pacific
area of high pressure will continue today, with a northerly flow
as the axis remains offshore. Low stratus and fog are still
expected today under the ridge with its continued inversion. An
approaching trough will begin to advance towards the area tonight,
helping to flatten the ridge during its approach, giving at least
a brief reprieve from the current inversion. The trough axis will
approach eastern Oregon on Friday afternoon, with the development
of showers possible though limited in coverage. Temperatures
across the valleys will remain 5-10 degrees below normal today,
with a few degrees of warming anticipated for Friday.

.LONG TERM...Friday night through Wednesday...An upper level
trough and associated cold front will push through the region
Friday night. Increased wind speeds and cold air aloft will work
to mix out the inversion that has been in place for the last 7-10
days. This allows temperatures to warm closer to normal especially
across the areas that have been locked in the low clouds and fog.
Otherwise, the upper ridge remains stationary around 130W and
amplifies somewhat northward. This pushes the stream of moisture
and thus precipitation mainly north of the forecast area bringing
generally dry and near normal conditions to the region through the
weekend. The moisture band sags further south into Valley and
Boise County Monday bringing the possibility of light snow fall to
that area.

Potential big changes expected for mid to late next week. Models
have been in good agreement and good run to run consistency in
indicating the potential for a strong cold front pushing into the
region Wednesday. Snow levels should lower to the valley floors with
light accumulations possible...higher accumulations in the
mountains. Winds may also be a concern as GFS BL winds showing 15-30
kts across the forecast area.


.AVIATION...Widespread low stratus and fog in the lower valleys,
with MVFR/IFR/LIFR conditions. Expecting inversion conditions to
continue today. Light and variable surface and extending aloft to
around 10KFT.





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